The boss of Europe's biggest airline by passenger numbers has warned some rival carriers could be driven out of business before the end of the year because of the impact the Iran war is having on global fuel prices.

In an interview with Italian newspaper Il Sole 24 Ore, Michael O'Leary, the famously outspoken CEO of budget carrier Ryanair, said that the fuel crisis had already cost his company an extra $50 million in April alone, amid warnings that the situation will only get worse after the busiest season for air travel across Europe has passed.

The price of jet fuel has more than doubled since the start of the Iran war, with the price per metric ton being $831 in February, and $1,838 in early April.

"If oil stays at these levels, two or three European airlines in October or November could go bankrupt, like (Hungary-based) Wizz Air, which wants to sue me but won't have enough time to do so, and (Latvia-based) airBaltic," O'Leary said, adding it is "a good thing for our business, because there will be fewer competitors".

A Wizz Air representative called O'Leary's comments "flatly false and untrue", telling the Euronews website that Wizz Air, with clear stability, is "one of the best hedged airlines in the industry against the rapidly changing fuel prices".

Instead, Wizz Air CEO Jozsef Varadi told The Daily Telegraph newspaper it was actually bigger airlines that would suffer most in the long term, in the inevitable tailing-off period that comes after the summer peak.

Some airlines with less strong fuel-hedging positions, such as Scandinavian Airlines and Germany's Lufthansa, have already scrapped thousands of planned flights.

In contrast to O'Leary's claims, Varadi said, "Airlines with weak liquidity positions will come under immense pressure in September time.

"No one is really taking capacity out during the summer because you are still making money. Winter is totally different. My personal expectation is that you will see a flood of capacity removed from the market in September and October time."